How to pass JWT-TOKEN to localStorage using JavaScript (script for html)?

I am writing a Rest MVC application for an online coffee and tea store. The following technologies are used: Spring-Boot, Hibernate, PostgreSQL, Gradle, Thymeleaf, HTML, CSS. I have the whole backend ready, it remains to make a frontend. At the moment I'm making an authorization page. The page itself is ready with HTML and CSS, now you need to make the authorization logic itself. To do this, I need to write a script in javascript so that my jwt token is stored in localStorage. The point is that I don't know how to implement this, how to pass my token through the header using javascripte in localStorage.

Important: javascript must be clean, without using frameworks (angular, node ...). How should I do it?

P.S. Again, the whole backand is ready. Rest-authorization method works (that is, I enter my login and password - I get a jwt token).

Java - authorization method

 public ResponseEntity<Map<String, String>> authorization(@RequestBody AuthenticationRequestDTO requestDto) {
        try {
            String login = requestDto.getLogin();
            authenticationManager
                    .authenticate(new UsernamePasswordAuthenticationToken(login, requestDto.getPassword()));

            User user = userRepository.getByLogin(login);

            if (user == null) {
                throw new AuthenticationServiceException("ddwd");
            }

            String token = jwtTokenProvider.createToken(login, user.getRole());

            Map<String, String> response = new HashMap<>();
            response.put("login", login);
            response.put("token", token);

            return ResponseEntity.ok(response);

        } catch (AuthenticationServiceException e) {
            log.error("Error: ", e);
            throw new AuthenticationServiceException("Invalid login");
        }
    }

You can add the JWT token in localstorage and retrieve/read and pass the value with your API calls. below is the example for setting and reading value from localstorage.

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script type="text/javascript">

function createLocalstorageItem(txtJwtTokenValue) {
  sessionStorage.setItem("jwtToken", txtJwtTokenValue);
}

function readValue() {
 var jwtToken = sessionStorage.getItem("jwtToken");
console.log("jwtToken : "+jwtToken );
return jwtToken ;

}
    
function getDataFromAPiByPassingJwtTokenInHeader(){
var jwtToken=readValue();
$.ajax({
    url: 'https://url.com',
    type: 'post',
    data: {},
    headers: {
        Bearer Token: "Bearer "+jwtToken,   //key word **Bearer**  should pass before the token string
    },
    dataType: 'json',
    success: function (data) {
        console.info(data);
    }
});
}

</script>

please try this way.